Forests: Changes in the Land

Introduction

The image to the right is from the Whitewater-Baldy Complex wildfire in Gila National Forest, New Mexico, as it burned on June 6th, 2012. Scientists calculate that high fire years like 2012 are likely occur two to four times per decade by mid-century, instead of once per decade under current climate conditions (NASA). Wildfires are just one phenomenon that can alter the land and in doing so, can alter the carbon cycle.

Approximately 50% of a tree's weight is comprised of carbon that originated from atmospheric carbon dioxide. What happens to this carbon when a tree burns, dies from drought or insect infestation, or is cut down to make way for agriculture? In this lab, you will explore answers to these important questions:

• How do changes in forests affect the carbon cycle?
• What can change forests from being a carbon sink to a carbon source?
• How can preserving forests help to mitigate the impact of elevated atmospheric CO₂ and climate change?

In Part A, you will analyze the impact of wildfires and deforestation on the carbon cycle.

In Part B, you will analyze the effects of wildfire on the carbon cycle of the Northern Boreal Forests and its relationship to climate change.

After completing this investigation, you will be able to:

• Describe how forests can function as a carbon sink or as a carbon source.
• Explain how wildfires, deforestation, and drought might change a forest from a carbon sink to a carbon source.
• Use systems thinking strategies to identify causal connections and feedbacks in a complex forest carbon cycle undergoing ecological change.

Keeping Track of What You Learn

Throughout these labs, you will find two kinds of questions.

• Checking In questions are intended to keep you engaged and focused on key concepts and to allow you to periodically check if the material is making sense. These questions are often accompanied by hints or answers to let you know if you are on the right track.
• Stop and Think questions are intended to help your teacher assess your understanding of the key concepts and skills you should be learning from the lab activities and readings.

Your teacher will let you know which answers you should record and turn in.